Piano action



J. c. DAVIS PIANO ACTION April 16, 1929.

Filed Dec. 9, 1926 2 Sheets-Sheet April 16, 1929. J, c, DAVIS 1,709,390

' PIANO ACTION FiledDec. 1926 2 Sheets-Sheet 2 Patented Apr. 16, i929.

UNETEED STATES PATE.

JOHN CARLYLE DAVIS, OF CINCINNATI, OHIO.

PIANO ACTION.

' Application filed December 9, 1926. Serial No. 153,666.

My invention relates to piano actions and has specific reference to the'provision of means for the operation of the back check, whereby the use of complicated escapement mechanism is obviated;

As at present constructed, piano actions comprise as a part of the hammer actuating and controlling mechanism more or less complicated mcchai lcal escapement mechanism for the hammer control by means of which the correct'relation between the hammer and back check is at all times maintained during the process of playing. This mechanism is actuated as is the hammer stroke, through the depression of the key, and by reason of the pressure required for the correct operation the escapement an uneven pressure is required upon the piano key. This uneven pressure must, of course, be taken into consideration by the performer in the rendition of a composition, and as this is at all times exceedingly difiicult, it makes the corroot and artistic rendition of a composition proportionately more difficult. Furthermore, the operation of such mechanisms-is the occasion of a certain amount of mechanical noise and disturbance in the instrument, which to some Xtent, especially in certain tone combinations as, for instance, trills, is detrimental to the artistic effect desired.

The principal object of the present invention is to provide electrical means for the back check control whereby the employment of mechanical cscapcment mechanism is entirely obviated and the difficulties above mentioned entirely overcome.

A further object of the present invention is to provide in connection with the means above mentioned, electrical means for the damper control whereby the added pressure of the piano key when it takes up the damper is eliminated, and the force required for the operation of the piano key is uniform throughout the entire stroke.

Further objects of the invention will appear from the following detailed description thereof.

In the drawings:

Figure 1 is an elevation ofa single piano key with its mountings and the related action constructed in accordancewith this invention.

Figure 2 is a plan view of a detail.

Figure 8 is a diagrammatic view showing electrical connections.

In the drawings, the numeral. 1 indicates the base or bed of a piano upon which the keys and action are supported, and 2 the metal framework or bracket for supporting the hammer mechanisms. Pivot lly mounted at 3 on the support 1 on bracket 2 is the wippen 5 for actuating the hammer shank 6, which latter carries the usual felt head 7 for striking the piano string 8. The shank 6 is pivotally mounted at 9 on a bracket 10' on the support 2. The wippen 5 carries an angularly extended arm 11 having a felt or other sound insulating head 12, which head bears against the hammer shank 6. The oppositeend of the wippen from the arm 11 carries the usual sound'insulating hammer shank rest 13. The wippen 5 is provided with a downwardly extending projection 14 which is arranged to rest on a head 15 car; ried by the inner end of the key 16. The head 15 is threaded onto a stud 1,7 for purposes of adjustment.

Pivotally mounted at 18 in the bed 1 is the shank 19 of the back check 20, said back check being arranged to engage the tail 7 of the hammer at the suitable time for the usual purpose; The shank 19 of the back check is provided with a spring 21 which normally draws the back check rearwardly away from hammer'engagement position. The base is provided with felt pads 22 to obviate any sound from the contactingof the shank with its support at the limit of either stroke.

For the purpose of instantaneously raising the key '16 after it has been depressed for the striking of a note, I provide on. the inner end of said key a spring which is arranged to be depressed by a finger 51 carried by the back check shank 19. When the key 16 is in its raised position the amount of clearance between the spring 50 and the head 52 on finger 51 is equal to the travel of the spring during complete depression of the key for striking a note; when, therefore, the key is depressed the spring in contact with the head 52, but is not under compression, such compression being effected by the forward movement of the back check as hereinafter set forth.

Pivotally mounted in a bracket 3 on the III vided with a pair of electrical contacts 27. The key above said contacts carries a contact ribbon connector 28, the interval be tween the said contacts and connector being such that the contact will be made approximately at the instant when the key reaches the lower end of its stroke. The bracket is provided with a pair of spring or ribbon contacts 29 between which connection is made by a copper arm 30 carried by the hammer shank (3, said arm being so spaced 'f om the sprin 's 29 as to establish the circuit at the proper instant as hereinafter mentioned. Mounted on the bracket 2 is a pair of contacts 31 between which connection is made by a thin spring or ribbon plate 82 carried by the back check shank l9. Mounted onJehe back cheek shank 19 is the armature 33 of a solenoizfl 34: which rests on the bed 1. Secured to the extension of lever 3% at its end opposite the grand dan'iper wire 25 is the armature of a solenoid 36 which also rests iipon the bed 1.

The connections between the contacts above described are illustrated diagrammatically in Figure 3 ol' the drawings. One of the contacts 27 is connected by means of a wire 37 to one terminal of a battery or other source of current supply 38. The other terminal of the battery 38 is connected by means of wire 39 to one terminal of the solenoid 34. The other terminal of the solenoid is connected. by wire 40 to one of the contacts 29, the other contact 29 being connected by means of a wire 41 to the other contact 27. Gne of the contacts 31 is connected by means of a wire 42 to wire ll; the other contact 31 is connected by means ot a wire 43 with wire 40. One terminal of solonoid 36 is connected by means of wire ill with one of the contacts 27, and the other terminal of said solenoid is connected by means of wire at with wire 39.

The operation of the device is 'as follows: \Vhcn the performer strikes the key 16 during the performance of a composition, the depression of said key makes contact at the bottom of its strike through plate 28 between the terminals 27. This contact closes the circuit through wire 37, battery 38 wires 39 and 4A, solenoid 36 and wire 4-3. The magnetic action of the solenoid raises the grand damper 26 in the usual manner. The actuation of the hammer shank 6 by the depression of the key 16, closes, by means of the plate 80, the circuit through the contacts 29 just before the hammer strikes the string, as follows: from contact- 27 through wire 41, the contacts 29, wire 40, solenoid 34:, wire 39, battery 38 and wire 37, to the other contact 27, the plate 28 being in contact by reason oi the depression of the key 16. The magnetic action of the solenoid 34 draws forward the back check shank 19 against the tension of sprim 1 so fact that the for ard as to bring the back check 20 to effective relation with respect to the hammer tail 7*. This action also compresses the spring carried by the inner end of the key so that said spring will instantaneously raise the key l6 upon release of: the finger pressure thereon. The hammer 7 upon striking the string 8 instantly rebounds, and the back check takws eliect in the usual manner; this rebound, however, opens the circuit between contacts 29 and the back check would be drawn backwa rdl y out oi. eli' ctivc posit ion by the tension of s1 "ing 21 were it not for the action of the bark check when actuat d through the closing of contacts 29 as above set forth, closes the circnit through the solenoid th ough he contacts 31 and plate as follows: .l'rom one of the contacts 27 through wires ell, and 42, contacts 31, plate 32, 're it}, solenoid :34- wire 3:) battery 38, and wire 37, to the other contact 27, and the e'll'cct ve posi he back check 20 is mainiaii'icd duringthe depression of the key as required or the proper operation oi the action. Upon release of pressure from the key 16, all circuits are opened between the contacts 27 and all mec anisms are permitted to return to their orig ial positions.

AS will be seen from the l'oregoin descriptioin I have provided electrically ac tuated back check and grand damper mechanism whereby the back check is operated without the necessity of intervening escapelnent mechanism, and the grand damper so actuated as to relieve the key ol the added pressure which it receives when the grand dam} er is taken up in mechanical actions.

It will furthermore be seen that through the elimination of the mechanical esc pcment and other mechanisms referred to, ill] necessity for unequal pressure upon the key 16 during its stroke is entirely obviated and that by reason thereof artistic eli'ccts may be greatly enhanced and imm'oved as well as mechanical noises and disturbances obviated.

Inasmuch as the key need only be raised to break the electrical contact between plate 28 and contacts 27 and not so high as isncw essary to reset an escapcment, repetition is greatly facilitated. lhu'thermoren the lriction and change of posit-ion in the escape mcnt mechanisms place a limit upon the d licacy or softness with which a note may be sounded, which ditliculty is overcome in the present action through the elimination ol? such escapement mechanism.

It will be understood that various changes and modifications may be made in the specific details above describeth and that such modifications are deemed a part of the pres ent invention as defined by the appended claims.

Having thus fully described my invenill) lee

lll)

tion, what I claim as new and desire to secure by Letters Patent 1s:

1. In a piano action, in combination with a hammer, a key arranged to operate said hammer, and a back check for said hammer, electrical means actuated by said key for the operation of said back check.

2. In a piano action, in combination with a hammer, a key arranged to operate said hammer, and a back chack tor-said hammer, electrical means actuated by said key and hammer for the actuation of said back check.

3. In a piano action, in combination with a hammer, a key arranged to operate said hammer, and a back check for said hammer, an electro-magnet arranged to actuate said back check, said electromagnet being provided with electrical connections adapted to be closed by the depression of said key.

4. In a piano action, in combination with a hammer, a key arranged to operate said hammer, and a back check for said hammer, an electromagnet arranged to actuate said back check, said electromagnet being provided with electrical connections arranged to be closed by the'depression of said'key and the consequent movement oi said hammer.

5. In a piano action, in combination with a hammer, a key arranged to operate said hammer, and a back check for said hammer, an electromagnet for the operation of said back check, electrical connections arranged to energize said electromagnet controlled by themevements of said hammer, and electrical connections for the energizing 01"- said magnet upon the actuation of said back check by said first mentioned connection to maintain an effective position of said back check when said first mentioned connections are opened.

6. In a piano action, in combination with a hammer, a key arranged to operate said hammer, and a back check for sald hammer,

an electromagnet for the actuation of said back check, electrical'contacts arranged to be closed by the depression of said key, electrical contacts arranged to be closed by the upward movement of said hammer, all of said contacts being connected in series with said magnet and a source of power supply.

7. In a piano action, in combination with a hammer, a key arranged to operate said hammer, and a back check for said hammer, an electromagnet for the actuation of said back check, electrical contacts arranged to be closed by the depression of said key, electrical contacts arranged to be closed by the upward movement of said hammer, all of said contacts being connected in series with said magnet and a source of power supply, and electricai contacts in series with said key contacts, electromagnet and source of supply, said last mentioned contact-s being arranged to be closed upon the actuation of said back check, and to short circuit said hammer contacts when so closed.

8. In a piano action, in combination with a hammer, a key arranged to operate said hammer, a back check for said hammer and a grand damper, electrical means arranged to be actuated by the depression of said key for the operation of said back check and- 

